Tropical Fish, Electric Blue Sick, lung infection?

This is a discussion on Tropical Fish, Electric Blue Sick, lung infection? within the Tropical Fish Diseases forums, part of the Freshwater Fish and Aquariums category; -->
Hi
Looking for help for friend
His 10 cm electric blue female past away this morning. :(
The male is down low gulping the ...

I'm going to say the same thing as I did in the other post, before I realized there were two:

Well, first off, which "electric blue?" There are four or five Malawi species that go by this common name.

As for the problem, gasping is a sign of a lack of oxygen in the tank. Have you tested the ammonia level in the tank? Adding an air pump or another filter to increase the surface movement of the water will help aerate it more.

the first post only says ammonia, we need nitrite and nitrate, what was the ph before you "hardened" the water, there might have been a dangerous ph drop for some reason, we need to know why, my biggest bet on why the fish is gulping is that there are nitrites in the water.

Sorry, didn't see the "nil ammonia" part in the OP. Anyway, I wouldn't be so quick to brush it off now that the fish is supposedly "back to normal." There is a reason one fish died, and a reason one fish was gasping - and it may not be fixed yet. I'd check the water for nitrites and nitrates as suggested.